Anderson R L, Herman T S, van Kersen I, Hahn G M
Department of Therapeutic Radiology, Stanford University, CA 94305.
Int J Radiat Oncol Biol Phys. 1988 Sep;15(3):717-25. doi: 10.1016/0360-3016(88)90317-3.
The magnitude of thermotolerance and the level of heat shock protein (HSP) expression have been measured in Chinese hamster ovary cells after gradual temperature transients from 37 degrees or 39 degrees to 42 degrees or 43 degrees C. When the level of thermotolerance was measured by clonogenic survival after challenging temperatures between 42 degrees and 43 degrees, substantial thermotolerance was observed. However, when the challenging temperature was raised to 45 degrees C, proportionally less thermotolerance was apparent. Heat shock proteins were quantitated by scanning densitometry of radiographs and, in the case of HSP 70, by immunoassay. Scanning densitometry revealed that low levels of heat shock proteins were synthesized during the heating gradients, but less than after a heat shock at 45 degrees C that delivered an equivalent heat dose. The immunoassay of HSP 70 levels measures both pre-existing and newly synthesized protein, and showed that there was net increase in HSP 70 during two of the heating gradients tested, despite the increase in synthesis noted on the gels. Higher turnover of HSP 70 at the elevated temperatures possibly accounted for the failure to detect a net gain in total protein. In contrast, the total amount of HSP 70 doubled during the 6 hr following a heat shock of 45 degrees for 10 min, an equivalent heat dose to one of the gradients where no net increase in HSP 70 was measured by immunoassay. It appears, then, that tolerance to hyperthemia at 43 degrees C or below may occur under some conditions in the absence of elevated levels of HSP 70, but tolerance to higher temperatures is more closely correlated with increased levels of heat shock proteins. However, even at higher temperatures, our data show disparities between the levels of HSP measured and the thermotolerance expressed.
在中国仓鼠卵巢细胞中，当温度从37℃或39℃逐渐升至42℃或43℃后，已对耐热性的程度和热休克蛋白（HSP）的表达水平进行了测定。当通过在42℃至43℃之间的挑战性温度下的克隆形成存活率来测量耐热性水平时，观察到了显著的耐热性。然而，当挑战性温度升至45℃时，耐热性则相应降低。通过对X光片进行扫描光密度测定对热休克蛋白进行定量，对于HSP 70，则通过免疫测定进行定量。扫描光密度测定显示，在升温梯度过程中合成的热休克蛋白水平较低，但低于在45℃热休克后合成的水平，45℃热休克所传递的热剂量与之相当。HSP 70水平的免疫测定可同时检测预先存在的和新合成的蛋白，结果显示，在两个测试的升温梯度过程中，HSP 70有净增加，尽管在凝胶上观察到合成有所增加。在升高的温度下，HSP 70的更新率较高，这可能是未能检测到总蛋白净增加的原因。相比之下，在45℃热休克10分钟后的6小时内，HSP 70的总量增加了一倍，该热剂量与其中一个升温梯度相当，在该升温梯度下，通过免疫测定未检测到HSP 70的净增加。因此，似乎在某些情况下，在HSP 70水平未升高的情况下，可能会出现对43℃及以下高温的耐受性，但对更高温度的耐受性与热休克蛋白水平的增加更密切相关。然而，即使在更高温度下，我们的数据也显示所测量的HSP水平与所表达的耐热性之间存在差异。
